Phosphatidylinositol 3-kinase is required for platelet-derived growth factor's actions on hepatic stellate cells
Phosphatidylinositol 3-kinase is required for platelet-derived growth factor's actions on hepatic stellate cells
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DOI：
10.1016/s0016-5085(97)70144-6
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发表时间：
1997-04-01
期刊：
影响因子：
29.4
通讯作者：
Gentilini, P
中科院分区：
文献类型：
--
作者：
Marra, F;Gentilini, A;Gentilini, P
背景与目的：血小板衍生生长因子(PDGF)是肝星状细胞(HSCs)最强的有丝分裂原。本研究旨在探讨磷脂酰肌醇3-激酶(PI3-K)激活在PDGF对体外培养的HSC的生物学效应中的作用及其在体内的作用。方法：从正常人肝脏分离HSCs。用体外磷酸化酪氨酸或PDGF受体免疫沉淀物测定pI3-K。结果：PDGF与HSCs孵育后，PI3-K活性呈时间依赖性增加。PDGF-α和-β受体的免疫沉淀显示，在PDGF刺激的HSCs中，这两个亚基都与活性的PI3-K结合。特异性PI3-K抑制剂Wortmannin可剂量依赖地阻断PDGF诱导的PI3-K活性，并抑制DNA合成。PDGF(Homodimer)-BB对HSC的趋化也有刺激作用，Wortmannin可抑制PDGF-BB的趋化作用。为了探讨PI3-K在体内的潜在作用，用抗PDGF-β受体抗体免疫沉淀CCl4处理的大鼠和对照大鼠的肝组织匀浆。肝损伤与PDGF-P受体自身磷酸化增加和PI3-K活性增加有关。结论：在体外培养的HSCs中，PI3-K的激活是PDGF诱导HSCs有丝分裂和趋化所必需的，在体内肝损伤过程中PI3-K信号通路上调。
Background & Aims: Platelet-derived growth factor (PDGF) is the most potent mitogen for hepatic stellate cells (HSCs) in vitro. The aim of this study was to investigate the role of phosphatidylinositol 3-kinase (PI 3-K) activation in mediating the biological effects of PDGF on cultured HSCs and its involvement in vivo. Methods: HSCs were isolated from normal human livers. PI 3-K was assayed on phosphotyrosine or PDGF-receptor immunoprecipitates by in vitro kinase assay. Results: Incubation of HSCs with PDGF caused a time-dependent increase in PI 3-K activity. Immunoprecipitation of PDGF-alpha and -beta receptors showed that both subunits associate with active PI 3-K in PDGF-stimulated HSCs. Wortmannin, a specific PI 3-K inhibitor, dose-dependently blocked PI 3-K activity induced by PDGF and inhibited DNA synthesis. PDGF (homodimer)-BB also stimulated HSC chemotaxis, which was inhibited by pretreatment with wortmannin. To explore the potential role of PI 3-K in vivo, liver homogenates from rats treated with CCl4 and from control rats were immunoprecipitated with anti-PDGF-beta-receptor antibodies. Liver injury was associated with increased PDGF-Preceptor autophosphorylation, and greater PI 3-K activity associated with the receptor itself. Conclusions: This study shows that in cultured HSCs, PI 3-K activation is necessary for both mitogenesis and chemotaxis induced by PDGF and that this pathway is up-regulated during liver injury in vivo.